JP3521820B2 - Cleaning device, piping cleaning method, refrigeration air conditioner and replacement method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning piping, and more particularly to a method for cleaning refrigerating machine oil remaining in the piping when the refrigerant used in a refrigerating and air-conditioning system is replaced with refrigerating machine oil. Is.

[0002]

2. Description of the Related Art FIG. 6 shows a separate type refrigerating and air-conditioning apparatus that has been generally used. In FIG. 6, 14
Is a heat source device, and includes a compressor 1, a four-way valve 3, a heat source side heat exchanger 10, a first operation valve 13a, a second operation valve 13b, and an accumulator 11. 15 is an indoor unit,
A flow rate regulator 17 (or a flow rate control valve) and a use side heat exchanger 18 are provided. The heat source unit 14 and the indoor unit 15 are installed at distant places and are connected by the first connecting pipe 5 and the second connecting pipe 7 to form a refrigeration cycle.

One end of the first connecting pipe 5 is connected to the four-way valve 3 and the first
Is connected via the operation valve 13a, and the other end of the first connection pipe 5 is connected to the utilization side heat exchanger 18. Second
One end of the connection pipe 7 is connected to the heat source side heat exchanger 10 via the second operation valve 13b, and the other end of the second connection pipe 7 is connected to the flow rate regulator 17. Further, an oil return hole 11 is provided in the lower part of the U-shaped tubular outflow pipe of the accumulator 11.
a is provided.

The flow of the refrigerant in this refrigeration / air-conditioning system will be described with reference to FIG. In the figure, the solid line arrow shows the flow of the cooling operation, and the broken line arrow shows the flow of the heating operation. First, the flow of the cooling operation will be described. The high-temperature and high-pressure gas refrigerant compressed by the compressor 1 flows into the heat source side heat exchanger 10 through the four-way valve 3 and exchanges heat with a heat source medium such as air and water to be condensed and liquefied. The condensed and liquefied refrigerant is used as the second operation valve 13b and the second connection pipe 7
And then flows into the flow rate regulator 17 where it is decompressed to a low pressure to form a low-pressure gas-liquid two-phase state, and is vaporized and gasified in the utilization side heat exchanger 18 by exchanging heat with a utilization side medium such as air.
The evaporated gasified refrigerant passes through the first connection pipe 5, the first operation valve 13a, the four-way valve 3 and the accumulator 11 and then the compressor 1
Return to.

Next, the flow of heating operation will be described. Compressor 1
The high-temperature and high-pressure gas refrigerant compressed by means of the four-way valve 3, the first operating valve 13a, and the first connecting pipe 5 flows into the heat exchanger 18 on the side of use, where the medium of heat on the side such as air and heat Replace and condense and liquefy. The condensed and liquefied refrigerant flows into the flow rate regulator 17, where it is decompressed to a low pressure and becomes a low-pressure gas-liquid two-phase state, and passes through the second connection pipe 7 and the second operation valve 13b and then to the heat source side heat exchanger. At 10, heat is exchanged with a heat source medium such as air and water to evaporate and gasify. The evaporated and gasified refrigerant returns to the compressor 1 via the four-way valve 3 and the accumulator 11.

[0006] Conventionally, most of such refrigerating and air-conditioning systems are CFC (chlorofluorocarbon) type refrigerants and HCFCs.
(Hydrochlorofluorocarbon) type refrigerants have been used, but since chlorine contained in these molecules destroys the ozone layer in the stratosphere, CFC type refrigerants have already been completely abolished, and
Production restrictions on CFC-based refrigerants have also started.

In place of these, a refrigerating and air-conditioning system using an HFC (hydrofluorocarbon) type refrigerant which does not contain chlorine in its molecule has been put into practical use. CFC type refrigerant and HC
When the refrigerating and air-conditioning system using the FC type refrigerant is aged, it is necessary to replace it with a refrigerating and air-conditioning system using the HFC type refrigerant because these refrigerants are completely abolished and production is regulated.

When the refrigerating and air-conditioning system is a separate type constituted by the heat source unit 14 and the indoor unit 15 and the connecting pipes 5 and 7 connecting them, the heat source unit 14 and the indoor unit 15 are
Since the refrigerating machine oil / organic material / heat exchanger used for the FC-based refrigerant is different from those of the HCFC-based refrigerant and the CFC-based refrigerant, it is necessary to replace it with a dedicated HFC-based refrigerant. Furthermore, originally, the heat source device 14 for CFC-based refrigerants and HCFC-based refrigerants
Since the indoor unit 15 is deteriorated and needs to be replaced, the replacement is relatively easy.

On the other hand, the connection pipes 5 and 7 are difficult to replace with new pipes when the pipes are long or buried in a building such as a pipe shaft or an overhead ceiling. CFC refrigerant and HCF
If the connection pipes 5 and 7 used in the refrigeration cycle apparatus using the C-based refrigerant can be used as they are, the piping work can be simplified.

However, the connecting pipes 5 and 7 used in the refrigerating and air-conditioning apparatus using the CFC-based refrigerant or the HCFC-based refrigerant have mineral oil, which is a refrigerating machine oil of the refrigerating and air-conditioning apparatus using the CFC-based refrigerant and the HCFC-based refrigerant, Remains.

FIG. 7 is a diagram showing a critical solubility curve showing the solubility of the refrigerating machine oil for HFC type refrigerant and the HFC type refrigerant (R407C) when mineral oil is mixed, in which the horizontal axis is the oil amount (wt%) and the vertical axis is. Indicates temperature (° C.). When the refrigerating machine oil is mixed with the refrigerant, it may be dissolved in the refrigerant to be compatible with it or may be separated without being dissolved, and the boundary point of compatibility and separation depends on the temperature. The compatible range is in the temperature range between the lower limit temperature and the upper limit temperature, and the dissolution characteristics are represented by the critical solubility curve in FIG. 7. Mineral oil is mixed in refrigerating machine oil (synthetic oil such as ester oil and ether oil) of a refrigerating and air-conditioning apparatus using an HFC-based refrigerant, and as the amount of the mineral oil increases, the compatible temperature range becomes narrower. When a certain amount or more is mixed, as shown in FIG. 7, the compatibility with the HFC-based refrigerant is lost, and when the liquid refrigerant is stored in the accumulator 11, the HFC-based refrigerant refrigeration oil is separated into the upper layer of the liquid refrigerant. Since it floats, the refrigerating machine oil may not return to the compressor from the oil return hole 11a in the lower part of the accumulator 11, and the sliding part of the compressor may be seized. Further, in the conventional CFC-based refrigerant, mineral oil was used as the lubricating oil, whereas in the HFC-based refrigerant, synthetic oil was used as the lubricating oil, so if the mineral oil remains in the existing refrigerant pipe, In the newly installed refrigerant circuit, there is a problem that foreign matter (contamination) occurs, blocking the throttle mechanism and damaging the compressor.

For this reason, CFC type refrigerants and HCFCs have been conventionally used.
The connection pipes 5 and 7 used in the refrigerating and air-conditioning system using the system refrigerant can be washed with the dedicated cleaning liquid (HCFC141b or HCFC225) that dissolves the mineral oil using the cleaning device. It is being appreciated.

[0013]

As described above, the conventional cleaning method has the following problems. First, the cleaning liquid used is an HCFC refrigerant and has an ozone depletion potential of 0.
Therefore, it is inconsistent with substituting the refrigerant of the refrigerating and air-conditioning system from the HCFC refrigerant to the HFC refrigerant. In particular, HC
FC141b has a large ozone depletion potential of 0.11, and there is a problem in cleaning piping using this refrigerant.

Secondly, the cleaning liquid used is not completely safe in flammability and toxicity. HCFC
141b is flammable, low toxicity, and HCFC2
25 is nonflammable but has low toxicity.

Third, since the cleaning liquid has a high boiling point (HCFC
141b is 32 ° C., HCFC225 is 51 to 56 ° C.) The cleaning liquid after cleaning is hard to evaporate and remains attached to the pipe. To recover these, blow the cleaning liquid with nitrogen gas to clean it. Requires.

Further, even if an attempt is made to perform cleaning using a cleaning liquid which does not cause environmental problems as described above or is easy to collect, there is almost no such cleaning liquid that is soluble in mineral oil. There was a problem that it was not done promptly.

The present invention has been made in order to solve the above problems, and provides a cleaning device and a cleaning method capable of cleaning pipes promptly and without environmental trouble, and used in a refrigerating and air-conditioning device. An object of the present invention is to provide a refrigerating and air-conditioning apparatus that simplifies the re-installation work of the pipe by cleaning the pipe when updating the device to replace the refrigerant and using the washed existing pipe.

[0018]

According to a first aspect of the present invention, there is provided a pipe cleaning method, wherein a cleaning medium that is incompatible or weakly compatible with refrigerating machine oil , which is an object to be cleaned , is discharged by a conveying means. A circulation flow is generated in the refrigerant circuit to change the state of the cleaning refrigerant into a gas-liquid two-phase mixed flow, and then the pipe to which the refrigerating machine oil is attached is cleaned with the gas-liquid two-phase mixed flow.

The pipe cleaning method according to claim 2 of the present invention is the pipe cleaning method according to claim 1, wherein the cleaning refrigerant is in a liquid state and has a density higher than that of the refrigerating machine oil which is an object to be cleaned and is in a gas state. The density is lower than that of the refrigeration oil , which is the object to be cleaned.

A pipe cleaning method according to claim 3 of the present invention is the pipe cleaning method according to claim 1 or 2, wherein the flow mode of the gas-liquid two-phase mixed flow of the cleaning refrigerant is an annular flow or It is a wavy flow.

A cleaning device according to a fourth aspect of the present invention includes a high-low pressure heat exchanger which is connected to a discharge side of a conveying means and which exchanges heat of a cleaning refrigerant to generate a gas-liquid two-phase mixed flow, and a gas-liquid two The pipe is washed with the gas-liquid two-phase mixed flow, which is provided with a decompression device that reduces the pressure before the mixed phase flow passes through the pipe to which the object to be cleaned adheres and flows into the high and low pressure heat exchanger again.

A cleaning device according to a fifth aspect of the present invention is the cleaning device according to the fourth aspect, which is connected to a conveying means for circulating and flowing out the cleaning refrigerant and a suction side of the conveying means, and is connected to a high-low pressure heat exchanger. The heat source side heat exchanger for cooling the outflowing cleaning refrigerant is provided, and the heat source side heat exchanger is connected to the high and low pressure heat exchanger to form a circuit.

A cleaning device according to claim 6 of the present invention is the cleaning device according to claim 4 or 5, wherein the cleaning device removes the object to be cleaned from the cleaning refrigerant passing through the pipe to which the object to be cleaned is attached. Is provided between the pipe and the conveying means.

The cleaning apparatus according to claim 7 of the present invention is the cleaning apparatus according to any one of claims 4 to 6, wherein the object to be cleaned is a chlorine-containing hydrochlorofluorocarbon (HCFC) type refrigerant or chlorofluorocarbon. It is a mineral oil used as a refrigerating machine oil that uses a fluorocarbon (CFC) -based refrigerant, and uses a hydrofluorocarbon (HFC) -based refrigerant, a hydrocarbon (HC) -based refrigerant, or a natural refrigerant that does not contain chlorine as a cleaning refrigerant.

A cleaning device according to claim 8 of the present invention is the cleaning device according to any one of claims 4 to 7, wherein R407C is used as an HFC refrigerant.

A cleaning apparatus according to claim 9 of the present invention is the cleaning apparatus according to any one of claims 4 to 7, wherein isobutane or propane is used as the HC refrigerant.

According to a tenth aspect of the present invention, there is provided a refrigerating and air-conditioning apparatus in which a pipe cleaned by the cleaning apparatus according to any one of the fourth to sixth aspects is provided with a compressor, a heat source side heat exchanger, a pressure reducing device, This is a pipe for connecting the indoor unit with the heat source unit of the refrigeration cycle to which the use side heat exchanger is connected.

A cleaning apparatus according to claim 11 of the present invention comprises:
The cleaning refrigerant is provided with a control means for adjusting the rotation speed of the conveying means for varying the circulating flow rate or for adjusting the opening degree of the decompression device, and the flow mode of the gas-liquid two-phase mixed flow of the cleaning refrigerant is changed to an annular flow or a wavy flow. Then, the inside of the pipe is washed .

According to a twelfth aspect of the present invention, there is provided a method for replacing a refrigerating and air-conditioning apparatus, wherein a refrigerating and air-conditioning apparatus using a refrigerant containing chlorine is separated into a heat source unit side, a user side and a connecting pipe.
In the meantime, a step of connecting a cleaning device composed of a high-low pressure heat exchanger and a pressure reducing device, a step of replacing and enclosing a refrigerant containing no chlorine on the heat source unit side, and a refrigerant in a high-low pressure heat exchanger The step of producing the mixed phase flow and introducing it to the user side and the connection pipe for cleaning.

According to a thirteenth aspect of the present invention, there is provided a method of replacing a refrigerating and air-conditioning apparatus according to the twelfth aspect of the present invention, wherein the refrigerant circuit is fully opened and forced on the user side and the connecting pipe. It does not exchange heat.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 shows the first embodiment.
3 is a refrigerant circuit diagram of the cleaning device according to FIG. In the figure, 1 is a compressor, 2 is an oil separator, 3 is a four-way valve, 4 is a high and low pressure heat exchanger, and 19 and 20 are existing pipes that connect the heat source unit of the refrigerating and air-conditioning system to the indoor unit. Piping performed, 6 is existing piping 1
By-pass pipe connecting one end of 9, 20, 8 is a pressure reducing device,
9 is a separation device for the object to be cleaned, 10 is a heat source side heat exchanger, 11
Is an accumulator. A cleaning device 12 includes a compressor 1, an oil separator 2, a four-way valve 3, a high / low pressure heat exchanger 4, a pressure reducing device 8, a separating device 9, and a heat source side heat exchanger 1.
0, accumulator 11, existing pipes 19, 2
The bypass pipe 6 of No. 0 is connected to the other end which is not connected via the operation valves 13a and 13b. Reference numeral 21 is a control means for adjusting the operating speed of changing the speed of the compressor 1 or adjusting the opening degree of the decompression device 8 in order to control the circulation flow rate and the flow state of the cleaning refrigerant.

In the present invention, the refrigeration cycle is configured as shown in FIG. 1, and R407C, which is an HFC mixed refrigerant, is used as the refrigerant circulating in the refrigeration cycle.
R407C has 23 / R32 / R125 / R134a
It is a non-azeotropic mixed refrigerant mixed in a ratio of 25/52 wt%, and as refrigerating machine oil, ester oil compatible with this refrigerant is used. The existing pipes 19 and 20 are HCFC
Refrigeration air conditioners using system refrigerants have been connected in the past,
Mineral oil, which is refrigerating machine oil for the HCFC refrigerant, remains in this existing pipe. The solubility of mineral oil in R407C is 1% or less, and it is almost insoluble in mineral oil.

Next, the cleaning procedure of the present invention will be described.
The air conditioner and the use side heat exchanger that are connected to the existing pipes 19 and 20 and need to be replaced are removed, and the cleaning device 12 and the bypass pipe 6 are connected to the existing pipes 19 and 20 as shown in FIG. After connecting, after vacuuming the entire refrigeration cycle, R40
Fill an appropriate amount of 7C. After that, the compressor 1 is operated and the flow direction of the four-way valve is set to the solid line direction in FIG. The operation status of the refrigeration cycle at this time is as follows. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 first passes through the oil separator 2. At this stage, the refrigerating machine oil discharged from the compressor 1 together with the gas refrigerant is separated by the oil separator 2 and returned to the suction side of the compressor 1. The high-temperature and high-pressure gas refrigerant then passes through the four-way valve 3, and the high- and low-pressure heat exchanger 4 partially cools the gas to become a liquid, which becomes a high-pressure gas-liquid two-phase refrigerant. This high-pressure gas-liquid two-phase refrigerant passes through the existing pipe 19, the bypass pipe 6, and the existing pipe 20, and then is decompressed by the decompression device 8 into a low-pressure gas-liquid two-phase refrigerant. After this, it is heated in the high and low pressure heat exchanger 4 to become a low pressure gas. Next, it passes through the separation device 9, and at this time, the mineral oil washed in the existing pipes 19 and 20 is separated, and the mineral oil is held in the separation device 9. The low-pressure refrigerant gas is cooled by the heat source side heat exchanger 10 so that the discharge temperature of the compressor 1 does not become too high, and then is sucked into the compressor 1 through the four-way valve 3 and the accumulator 11.

By operating the refrigeration cycle in this manner, it becomes possible to flow a gas-liquid two-phase mixed flow, that is, a refrigerant in which gas and liquid are mixed, in the existing pipe. Here, the reason why the gas-liquid two-phase refrigerant is caused to flow through the existing pipe for cleaning will be described. FIG. 2 is a graph showing the cleaning characteristics of mineral oil for each state of the refrigerant during cleaning in the present invention, where the horizontal axis represents the cleaning time and the vertical axis represents the amount of mineral oil remaining in the pipe after cleaning.
When cleaning mineral oil as shown in Fig. 2, among the three states of gas single-phase, liquid single-phase, and gas-liquid two-phase (gas-liquid mixture), cleaning characteristics when cleaning with gas-liquid two-phase It turns out that is excellent. In the conventional cleaning, a cleaning liquid such as HCFC225 is poured as a liquid into a pipe, and the cleaning liquid dissolves mineral oil for cleaning. When R407C is washed by flowing it, as in the conventional case, when it is poured as a liquid in the pipe and washed, since it has almost no solubility, mineral oil is pulled and moved by the shearing force with R407C to be washed. .
In this case, the moving speed of the mineral oil is remarkably slower than the flow speed of the refrigerant liquid, and it takes a long time to perform the cleaning, which is not practical. There is also a method of flowing R407C into the pipe as a gas, but in this case as well, mineral oil is pulled and moved by a shearing force with R407C in the same manner for cleaning, and the moving speed of mineral oil is slow and it takes time to perform cleaning. It is not practical. on the other hand,
In the case of cleaning with the gas-liquid two-phase mixed flow, the two-phase flow causes the gas-liquid to mix and flow, so that the turbulence of the flow becomes larger than that in the case of flowing the liquid single phase and the gas single phase. Therefore, the turbulence of the liquid refrigerant in the gas-liquid two-phase refrigerant becomes large near the wall surface of the pipe, and the mineral oil adhering to the wall surface is peeled off from the wall surface. Since the mineral oil peeled off from the wall surface moves in the refrigerant, the moving speed becomes the same as that of the refrigerant. Therefore, the refrigerant can be moved at a higher speed as compared with the case where the refrigerant is pulled and moved by the shearing force with R407C to be washed, and the mineral oil is quickly washed in a short time. It should be noted that the cleaning characteristics of mineral oil depend on the ability to strip the mineral oil from the pipe. The ability to strip mineral oil is determined by the turbulence of gas-liquid two-phase flow, which is determined by the proportion of liquid, gas in the two-phase flow and the flow velocity of the two-phase flow. Therefore, the conditions for flowing these two-phase flows are determined by how long and how much mineral oil in the pipe is washed.

After the completion of cleaning the pipe, the operation of the compressor is stopped, the flow direction of the four-way valve is set to the dotted line direction in FIG.
The operation valve 13b is closed. Then, when the compressor is operated again, the second operation valve 13b is closed, so that the refrigerant discharged from the compressor 1 is driven into the heat source side heat exchanger 10, the separation device 9, etc. and accumulated, Meanwhile, existing piping 19,
The refrigerant in 20 and the bypass pipe 6 is drawn out to the accumulator 11, and the so-called pump down operation is performed to recover the R407C remaining in the existing pipes 19 and 20. R4
Since the boiling point of 07C is as low as −43 ° C., it is easily vaporized and gasified by performing this pump down operation, so that R407C as a cleaning liquid can be easily recovered. After the pump down operation is completed, the first operation valve 13a is closed and R
The collection of 407C is completed.

After the recovery of R407C, the cleaning device 12 and the bypass pipe 6 are removed from the existing pipe, the heat source unit 14 and the indoor unit 15 which are newly installed after replacement are attached, and the cleaning of the existing pipe and the replacement of the refrigeration / air-conditioning system are completed. . By doing so, it becomes possible to easily replace the refrigerating and air-conditioning device without re-installing the pipe. Further, in the cleaning device, the means for conveying the cleaning refrigerant to the circuit is not limited to the compressor, but may be a liquid pump and can be selected according to the characteristics of the cleaning refrigerant.

Embodiment 2. FIG. 3 is a diagram showing a second embodiment of the present invention and is a refrigerant circuit diagram of a cleaning device. In the figure, the same reference numerals as those in FIG.
Is composed of a compressor 1, an oil separator 2, a four-way valve 3, a heat source side heat exchanger 10, and an accumulator 11.
Reference numeral 6 includes a high and low pressure heat exchanger 4, a pressure reducing device 8 and a separating device 9. Further, 13a and 13b are operation valves for connecting the mineral oil recovery device 16 and the existing pipes 19 and 20, 13c, 13d and 1
3e and 13f are connection valves that connect the heat source device 14 and the mineral oil recovery device 16. Instead of the cleaning device 12 shown in FIG.
Cleaning is performed by combining the heat source device 14 and the mineral oil recovery device 16 installed after the replacement. The refrigeration cycle configured in FIG. 3 has the same configuration as in FIG.
The same effect as above can be obtained, and the cleaning can be similarly performed. After the cleaning is completed, the mineral oil recovery device 16 and the bypass pipe 6 are removed, and the existing pipes 19 and 20 are connected to the heat source device 14 and the indoor unit 15 to complete the cleaning of the pipes and the replacement of the refrigeration / air-conditioning device.

If the device for opening and closing the refrigerant circuit of the flow rate regulator 17 as shown in FIG. 6 provided in the indoor unit 15 is fully opened and the heat exchange blower is de-energized, it is connected in series with the existing pipe. It becomes possible to wash the refrigerant circuit at the same time by connecting to.

Note that, as long as the cleaning refrigerant can be supplied to the existing pipes 19 and 20 in a gas-liquid two-phase mixed flow, the pipes can be cleaned without being limited to the above-described structure.

R407 is used as a cleaning refrigerant for cleaning the piping.
Not limited to C, other HFC-based single or mixed refrigerants may be used, such as R32 (slightly flammable / non-toxic) and R12.
5 (nonflammable / nontoxic), R134a (nonflammable / nontoxic), R
Cleaning may be performed with 410A (nonflammable / nontoxic) and R404A (nonflammable / nontoxic). Alternatively, an HC-based refrigerant such as propane or butane and a mixed refrigerant thereof, or a natural refrigerant such as ammonia, carbon dioxide, or water may be used. Further, the two-phase flow is not limited to the combination of the gasified liquid of the same cleaning liquid and the cleaning liquid, and different types of gas and liquid may be combined. For example, cleaning may be performed with a two-phase flow in which air and water are mixed.

Embodiment 3. Hereinafter, a third embodiment of the present invention
Will be described. In the third embodiment of the present invention, cleaning is performed as shown in FIG. 1, and R407C gas is used as a cleaning refrigerant.
A gas-liquid two-phase mixed flow in which the liquids are mixed is used to wash the residual mineral oil in the piping. R40 used as a cleaning refrigerant at this time
The pressure at the existing pipe inlet of 7C is 15 kgf / cm ² ab
The cleaning conditions are set so as to be s. At this time R407
The density of the C liquid is 1100 kg / m ³ , and the density of the R407C gas is 66 kg / m ³ . The density of mineral oil is 900k
a g / m ^3, the density of R407C liquid is greater than the density of the mineral oil.

Here, in an in-pipe flow such as the internal flow of a pipe, generally, the velocity at the center of the pipe is high, and the velocity becomes slower as it gets closer to the pipe wall. At this time, consider the kinetic energy when a mixture of high density and low density flows. The one with a high density flows in the center of the pipe and the one with a low density flows near the pipe wall, while the one with a low density flows in the center of the pipe and the one with a high density flows near the pipe wall. Comparing the cases, when the density is high in the center of the tube and the density is low near the wall of the tube, the flow velocity of the density is high and the kinetic energy is high. Generally, a fluid flows so that the energy of the fluid decreases, so when a mixture of high density and low density flows together, a fluid with a low density flows through the center of the pipe so that the kinetic energy is low. Flows near the tube wall.

When cleaning is performed with a gas-liquid two-phase mixed flow, the mineral oil adhering to the wall surface is peeled off and moved by the liquid as described above. After that, if the density of the liquid is lighter than that of the mineral oil, the mineral oil easily flows near the wall surface, and redeposition is likely to occur. When reattached, the movement of the mineral oil is due to the shearing force, so the movement speed becomes slow and it takes time to wash.

However, when R407C is used as the cleaning liquid as in the third embodiment and the cleaning conditions are set so that the density of the liquid of R407C is higher than the density of the mineral oil, the mineral oil is peeled off by the liquid and then the mineral oil is liquefied. Since it flows through the pipe at a position away from the wall surface and closer to the center of the pipe, it does not reattach to the wall surface. Therefore, the mineral oil moves at the same speed as the cleaning liquid, which enables quick cleaning.

Here, FIG. 4 is a diagram showing the flow pattern of the gas-liquid two-phase mixed flow. In FIG. 4, (a) shows a flow state in which the liquid-phase flow rate is small, and gas-liquid two-phase uneven flow called a stratified flow, a corrugated flow, and an annular flow is large, while (c)
Is a case where the liquid phase flow rate is large, and is a flow state in which gas-liquid two phases called a bubbly flow and an annular spray flow are mixed and stirred. When the pipe is a horizontal pipe, as a two-phase flow, as shown in FIG. 4, a gas may be in a flow state called a wavy flow in which the gas flows in the upper part of the pipe and the liquid flows in the lower part of the pipe. At this time, if the density of the mineral oil is lower than the gas density of R407C, the peeled mineral oil floats to the upper part due to the effect of gravity and redeposits on the upper part of the pipe, which slows down the cleaning speed. Since the gas density of R407C is smaller than that of mineral oil, the peeled mineral oil moves between the gas phase and the liquid phase due to the effect of gravity even in a flow like a wavy flow. The same speed,
Quick cleaning is possible.

Fourth Embodiment Fourth Embodiment of the Present Invention
Will be described. In the fourth embodiment of the present invention, cleaning is performed as shown in FIG. 1, and R407C gas is used as a cleaning refrigerant.
A gas-liquid two-phase mixed flow in which the liquids are mixed is used to wash the residual mineral oil in the piping.

The gas-liquid two-phase flow flowing in the tube can be classified as shown in FIG. In the fourth embodiment, cleaning is performed so that the flow state is represented by a wavy flow (stratified flow) or an annular flow. When cleaning is performed in a wavy flow (stratified flow), as described above, after the mineral oil is peeled off from the wall surface, the mineral oil moves between the gas phase and the liquid phase due to the effect of gravity, so the movement speed of the mineral oil is The speed is the same as that of the product, and it is possible to wash quickly. When flowing in an annular flow, the mineral oil peeled off from the wall surface flows between the liquid and the gas due to the relationship between the densities of the liquid, the gas and the mineral oil, and the kinetic energy of the fluid. Therefore, the moving speed of the mineral oil becomes the same as that of the cleaning refrigerant, and the cleaning can be carried out quickly. Further, since the same effect as the annular flow can be obtained with the annular spray flow, the cleaning may be performed with the annular spray flow. On the other hand, in other flow modes, in particular, in the bubbly flow, the proportion of gas in the two-phase flow is low, so that the turbulence of the flow is lower than that in the wavy flow or the annular flow. Therefore, the ability to peel off the mineral oil adhering to the wall surface becomes lower than that of the wavy flow or the annular flow. Further, in the case of horizontal piping, in the bubbly flow, the density of the cleaning liquid is higher than the density of mineral oil, and therefore the mineral oil flows through the upper portion of the piping due to the effect of gravity. In this case, the mineral oil peeled off from the pipe is likely to reattach to the upper portion of the pipe, resulting in a long cleaning time, which is unsuitable for cleaning.

The flow pattern of the two-phase flow is R
It is determined by cleaning conditions such as the flow rate of 407C and the ratio of liquid gas. FIG. 5 is called a Baker diagram showing the flow pattern of gas-liquid two-phase flow. The ordinate and the abscissa of FIG. 5 are values showing the flow state of the refrigerant, and the ordinate shows the magnitude of the mass flow rate of the refrigerant, and the values increase toward the top. The horizontal axis represents the ratio of the gas mass flow rate of the refrigerant to the liquid mass flow rate, that is, the dryness. The dryness decreases toward the right and the liquid becomes rich. From this diagram, the conditions for flowing in the annular flow and the wavy flow (stratified flow) are clarified, and the cleaning conditions can be determined. For example, R407C of the present invention
In the case of, the mass flow rate corresponding to the flow velocity is 100 to 300.
[Kg / m ² · s], ratio of liquid gas, that is, dryness (=
Mass flow rate of gas / (mass flow rate of gas + mass flow rate of liquid))
Is controlled to be 0.2 or more, the operating frequency control for changing the rotation speed of the compressor, which is the conveying means, or the opening adjustment control for the pressure reducing device is performed. In addition to the Baker diagram, there are diagrams showing several flow patterns such as the Mandhane diagram, and the washing conditions may be determined based on the diagram.

In addition, in the removal of pipe deposits by the separation effect using the gas-liquid two-phase flow, the water plug is used to alternately press the cleaning liquid and the air using the liquid feed pump and the compressed air into the pipe at predetermined intervals. Although there is cleaning by the method, in comparison with this, the circulating refrigerant by the compressor is changed in state to make the gas-liquid two-phase flow flowing through the pipe into an annular flow or wavy flow, so that the device is simple. You can

[0050]

The pipe cleaning method according to claim 1 of the present invention discharges the cleaning refrigerant, which is incompatible or weakly compatible with the refrigerating machine oil , which is the object to be cleaned, into the refrigerant circuit by discharging the cleaning refrigerant. A circulation flow is generated, the state of the cleaning refrigerant is changed to a gas-liquid two-phase mixed flow, and then the pipe with the refrigerating machine oil is cleaned with the gas-liquid two-phase mixed flow, so there is no need to use a cleaning liquid that has environmental problems. Also, the existing pipes can be washed promptly.

The pipe cleaning method according to claim 2 of the present invention is the pipe cleaning method according to claim 1, wherein the cleaning refrigerant is in a liquid state and has a density higher than that of the refrigerating machine oil which is the object to be cleaned and is in a gas state. Since the one to be cleaned has a lower density than the refrigerating machine oil, it prevents re-adhesion after peeling off the to-be-cleaned object, and it can be moved in the same speed as the cleaning liquid refrigerant and cleaned in a short time. .

A pipe cleaning method according to claim 3 of the present invention is the pipe cleaning method according to claim 1 or 2, wherein the flow mode of the gas-liquid two-phase mixed flow of the cleaning refrigerant is an annular flow or Since the flow is wavy, it is possible to quickly clean the existing pipe.

A cleaning apparatus according to a fourth aspect of the present invention comprises a high-low pressure heat exchanger which is connected to the discharge side of the conveying means and which exchanges heat with the cleaning refrigerant to generate a gas-liquid two-phase mixed flow, and a gas-liquid two-phase heat exchanger. It is equipped with a decompression device that reduces the pressure before the phase-mixed flow passes through the pipe with the object to be cleaned and flows into the high-and-low pressure heat exchanger again. It is possible to quickly clean the existing pipe without using a problematic cleaning liquid.

A cleaning apparatus according to a fifth aspect of the present invention is the cleaning apparatus according to the fourth aspect, which is connected to a conveying means for circulating and flowing out the cleaning refrigerant and a suction side of the conveying means, and is connected to a high-low pressure heat exchanger. The heat source side heat exchanger for cooling the outflowing cleaning refrigerant is provided, and since the heat source side heat exchanger is connected to the high and low pressure heat exchanger to form a circuit, without being limited to the refrigerant used after the re-use, It is possible to quickly clean the existing pipe using another cleaning refrigerant that does not cause environmental problems.

A cleaning device according to claim 6 of the present invention is the cleaning device according to claim 4 or 5, wherein the cleaning device removes the object to be cleaned from the cleaning refrigerant that has passed through the pipe to which the object to be cleaned adheres. Is provided between the pipe and the conveying means, it is possible to efficiently collect the object to be cleaned and prevent clogging of the refrigerant circuit due to the object to be cleaned and seizure failure of the sliding part of the conveying means.

A cleaning device according to claim 7 of the present invention is the cleaning device according to any one of claims 4 to 6, wherein the device to be cleaned is a hydrochlorofluorocarbon (HCFC) -based refrigerant or chlorine containing chlorine. It is a mineral oil used as a refrigerating machine oil that uses a fluorocarbon (CFC) -based refrigerant, and as a cleaning refrigerant, a hydrofluorocarbon (HFC) -based refrigerant or a hydrocarbon (HC) -based refrigerant or a natural refrigerant that does not contain chlorine is used. It is possible to quickly clean the existing pipe without using a problematic cleaning liquid.

The cleaning apparatus according to claim 8 of the present invention is the cleaning apparatus according to any one of claims 4 to 7, in which R407C is used as the HFC refrigerant, so that a cleaning solution that is environmentally problematic is used. Even without it, the cleaning of the existing pipe can be carried out promptly.

The cleaning device according to claim 9 of the present invention is the cleaning device according to any one of claims 4 to 7, in which isobutane-based or propane-based refrigerant is used as the HC-based refrigerant. It is possible to quickly clean the existing pipe without using a certain cleaning liquid.

According to a tenth aspect of the present invention, there is provided a refrigerating and air-conditioning apparatus in which a pipe cleaned by the cleaning apparatus according to any one of the fourth to sixth aspects is provided with a compressor, a heat source side heat exchanger, a pressure reducing device, Since it was a pipe connecting the heat source unit and the indoor unit of the refrigeration cycle connected to the use side heat exchanger, when updating the device to replace the refrigerant used in the refrigerating air conditioner,
The re-installation work of the pipe can be simplified.

The cleaning apparatus according to claim 11 of the present invention is
The cleaning refrigerant is provided with a control means for adjusting the rotation speed of the conveying means for varying the circulating flow rate or for adjusting the opening degree of the decompression device, and the flow mode of the gas-liquid two-phase mixed flow of the cleaning refrigerant is changed to an annular flow or a wavy flow. Then, since the inside of the pipe is cleaned , the existing pipe can be promptly cleaned.

According to a twelfth aspect of the present invention, there is provided a method for replacing a refrigerating and air-conditioning apparatus, wherein a refrigerating and air-conditioning apparatus using a refrigerant containing chlorine is separated into a heat source unit side, a user side and a connecting pipe.
In the meantime, a step of connecting a cleaning device composed of a high-low pressure heat exchanger and a pressure reducing device, a step of replacing and enclosing a refrigerant containing no chlorine on the heat source unit side, and a refrigerant in a high-low pressure heat exchanger Since it has a step of generating a mixed phase flow and guiding it to the user side and connecting pipes for cleaning, the existing refrigerating air conditioner can be cleaned efficiently and promptly without using a cleaning solution that is environmentally problematic. Therefore, the work efficiency can be reduced.

According to a thirteenth aspect of the present invention, there is provided a method for replacing a refrigerating and air-conditioning apparatus according to the twelfth aspect, wherein the refrigerant circuit is fully opened and forced on the user side and the connecting pipe. Since heat exchange is not performed, it is possible to wash the existing pipes and the indoor unit side in a short time without using a washing solution that is environmentally problematic.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a cleaning device showing a first embodiment of the present invention.

FIG. 2 is a geraph showing a relationship between a residual oil amount in a pipe and a cleaning time in the cleaning apparatus of FIG.

FIG. 3 is a refrigerant circuit diagram of a cleaning device showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a flow pattern of a gas-liquid two-phase flow according to the third and fourth embodiments.

FIG. 5 is a characteristic diagram showing a flow state of a gas-liquid two-phase refrigerant in an existing pipe according to the fourth embodiment of the present invention.

FIG. 6 is a refrigerant circuit diagram of a conventional refrigeration / air-conditioning system.

FIG. 7 is a relationship diagram of a critical solubility curve showing solubility of a HFC refrigerating machine oil and an HFC refrigerant when a conventional refrigerating machine oil (mineral oil) is mixed.

[Explanation of symbols]

1 compressor, 2 oil separator, 3 four-way valve, 4 high and low pressure heat exchanger, 5 first connecting pipe, 6 bypass pipe, 7 second connecting pipe, 8 pressure reducing device, 9 separating device, 10 heat source side heat Exchanger, 11 Accumulator, 12 Cleaning device, 13a 1st operation valve, 13b 2nd operation valve, 1
3c, 13d, 13e, 13f connection valve, 14 heat source device, 15 indoor unit, 16 mineral oil recovery device, 17 flow rate regulator, 18 utilization side heat exchanger, 19, 20 existing pipe, 2
1 Control means.

─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Naoki Tanaka 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Seiji Inoue 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric (56) References JP-A-6-86907 (JP, A) JP-A-11-182991 (JP, A) JP-A-4-265370 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 47/00 B08B 9/027 F25B 45/00

Claims (13)

(57) [Claims] 1. A cleaning refrigerant that is incompatible or weakly compatible with refrigerating machine oil , which is an object to be cleaned , is discharged by a conveying means to generate a circulating flow in a refrigerant circuit, and the cleaning refrigerant is vapor-liquid two-phase. A method for cleaning a pipe, characterized in that after the state is changed to a mixed flow, the pipe to which the refrigerating machine oil adheres is washed with the gas-liquid two-phase mixed flow. 2. When the cleaning refrigerant is in a liquid state, it is an object to be cleaned.
Greater density than a refrigerating machine oil, and pipe cleaning method according to claim 1, wherein the density is less than the refrigerating machine oil to be cleaned in the gaseous state. 3. The pipe cleaning method according to claim 1, wherein the flow mode of the gas-liquid two-phase mixed flow of the cleaning refrigerant is an annular flow or a wave upstream. 4. A high / low pressure heat exchanger which is connected to the discharge side of the conveying means and exchanges heat with a cleaning refrigerant to generate a gas-liquid two-phase mixed flow, and the gas-liquid two-phase mixed flow adheres to an object to be cleaned. And a pressure reducing device for reducing the pressure before flowing into the high and low pressure heat exchanger again, and cleaning the pipe with the gas-liquid two-phase mixed flow. 5. Conveying means for circulating and flowing out the cleaning refrigerant,
A heat source side heat exchanger that is connected to the suction side of the conveying means and cools the cleaning refrigerant flowing out from the high and low pressure heat exchanger,
The cleaning device according to claim 4, wherein the heat source side heat exchanger is connected to the high and low pressure heat exchanger to form a circuit. 6. The separation device for removing the object to be cleaned from the cleaning refrigerant that has passed through the tube to which the object to be cleaned has adhered is provided between the pipe and the conveying means. The cleaning device according to. 7. The object to be cleaned is a mineral oil used as a refrigerating machine oil that uses a hydrochlorofluorocarbon (HCFC) -based refrigerant or a chlorofluorocarbon (CFC) -based refrigerant containing chlorine, and the cleaning refrigerant does not contain chlorine. The cleaning apparatus according to any one of claims 4 to 6, wherein a hydrofluorocarbon (HFC) -based refrigerant, a hydrocarbon (HC) -based refrigerant, or a natural refrigerant is used. 8. The cleaning device according to claim 4, wherein R407C is used as the HFC refrigerant. 9. The cleaning device according to claim 4, wherein an isobutane type or a propane type is used as the HC type refrigerant. 10. A pipe that has been cleaned in the cleaning device according to any one of claims 4 to 6, compressors, heat source side heat exchanger, a decompression device, a refrigeration cycle that connects the utilization-side heat exchanger A refrigerating and air-conditioning device, characterized in that it is a pipe connecting between the heat source unit and the indoor unit. 11. A control means for adjusting the number of revolutions of a conveying means for varying the circulation flow rate of the cleaning refrigerant or for adjusting the opening degree of a decompression device, the flow mode of the gas-liquid two-phase mixed flow of the cleaning refrigerant is provided. and an annular flow or wavy flow, to clean the inside of the pipe
Cleaning apparatus, characterized in that that. 12. A refrigeration / air-conditioning system using a refrigerant containing chlorine is separated into a heat source machine side, a user machine side and a connection pipe,
In the meantime, a step of connecting a cleaning device composed of a high and low pressure heat exchanger and a pressure reducing device, a step of substituting and enclosing a refrigerant that does not contain chlorine on the heat source unit side, and a vapor of the refrigerant in the high and low pressure heat exchanger. A method for replacing a refrigerating and air-conditioning apparatus, the method comprising: producing a liquid two-phase mixed flow, and then introducing the liquid two-phase mixed flow to the user side and connection pipes for cleaning. 13. The method of replacing a refrigerating and air-conditioning apparatus according to claim 12, wherein the refrigerant circuit is fully opened and the forced heat exchange is not performed on the user side and the connection piping.